EP0016262B2 - Process for consolidating and sealing geological and heaped rock and earth formations - Google Patents

Description

• Zeitschrift Glückauf (1968), S. 666-670 ;
• Zeitschrift Glückauf (1977), S. 707-711 ;
• Zeitschrift Bergbau (1977), S. 124-129 ;
• DE-A-1 758 185 ; DE-A-1 784 458.

The consolidation and sealing of geological and poured rock and earth formations takes place in underground coal mining to a very large extent using polyurethane systems, cf.

• Glückauf magazine (1968), pp. 666-670;
• Glückauf magazine (1977), pp. 707-711;
• Bergbau magazine (1977), pp. 124-129;
• DE-A-1 758 185; DE-A-1 784 458.

As a rule, two-component polyurethane systems are pressed into the formations to be consolidated, technical polyisocyanates on the one hand and polyols with a molecular weight of 400-600 and an OH number of 350 to 400 generally serving as starting components. According to DE-A-2 436 029, the polyols are made more flexible with polyols having an OH number between 50 and 90 and a molecular weight of 2,000-35,000.

Water-bearing rock formations are a natural limitation of the possible uses of polyurethane, since the water destroys the polyisocyanate and thus decisively disturbs the stoichiometric ratio of the reactants. In addition, water and polyisocyanate preferably form polyurea, which does not adhere to crevices and cracks in the mountains. Again and again it is pointed out that the water should be kept away from the mountain areas to be hardened when hardening with polyurethane. Cf. Glückauf magazine (1972), pp. 10-13.

A fundamental disadvantage of using polyurethane in coal mining is that the cured product burns easily. If there are large amounts of cured polyurethane in coal fissures, auto-ignition fires of coal can spread further through the polyurethane. Attempts have therefore been made to overcome the disadvantages of polyurethane by using systems which are practically non-flammable and are in aqueous form so that they can also be solidified in moist and wet formations.

So z. B. Experiments have been carried out to a considerable extent with aqueous formaldehyde-urea solutions. However, sufficient strengthening could not be achieved with these systems, since the resulting products shrink very strongly during the curing process.

Attempts have also been made to use water glass solutions for solidification. Water glass solutions require the addition of hardening agents to harden. Acidic or acid-forming substances such as phosphoric acid, sulfonic acid, esters such as. e.g. B. glycerol triacetate, ethyl acetate and other organic substances such as formamide, glyoxal. Calcium chloride, aluminum sulfate, magnesium chloride, magnesium sulfate, aluminum chloride and silicon fluoride are also used as hardeners.

Coarse medium sands and gravel z. B. solidify to a certain extent for the purpose of building ground consolidation; Solidifications with a high degree of solidification are therefore not possible, since a considerable volume shrinkage occurs during the hardening of water glass and, as a result, the composite body detaches from the surfaces of the cracks and gaps.

The present invention solves the problem of creating a method for solidifying and sealing geological and poured rock and earth formations which avoids the described disadvantages of the solidification methods of the prior art, achieves satisfactory solidification values, is insensitive to moisture and is non-combustible.

This object is achieved according to the invention in that water glass solutions and polyisocyanates selected from the group consisting of (i) polyphenyl-polymethylene polyisocyanates as produced by aniline / formaldehyde condensation and subsequent phosgenation, and (ii) carbodiimide groups, biuret groups, Derivatives of these polyisocyanates which contain urethane groups or allophanate groups and are liquid at room temperature, are intimately mixed with one another and this emulsion is introduced into the geological formation to be consolidated under pressure via boreholes or injection lances and allowed to harden in the formation to be consolidated. The adhesion of the solid to dry and wet geological formations is excellent, especially since the shrinkage that occurs during the hardening of water glass solutions without the addition of polyisocyanate does not occur at all and instead the adhesion is promoted by a certain increase in volume during the hardening. Of particular advantage for coal mining is that the hardened solidifying agent is non-flammable and achieves excellent strength for the stabilization of the formation of the composite bodies which form in gaps and the like.

Surprisingly, hardened composite bodies also adhere to greasy, that is to say relatively high bitumen-containing coal, so that good strengthening is achieved in any type of coal.

Suitable polyisocyanates according to the invention are organic polyisocyanates with aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic bound polyisocyanate groups, as described, for. B. by W. Siefken in "Justus Liebigs Annalen der Chemie", 562, pages 75-136. In particular, however, the usual in polyurethane chemistry, liquid at room temperature polyisocyanates with aromatically bound polyisocyanate groups are used, such as. B. 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, and any mixtures of these isomers («TDI •), polyphenyl-polymethylene polyisocyanates, such as those caused by aniline / formaldehyde condensation and subsequent phosgenation are produced (“MDI”) or also cabodiimide groups, biuret groups, urethane groups or allophanate groups and derivatives of these polyisocyanates which are liquid at room temperature. The polyisocyanate mixture («MDI») which is liquid at room temperature and obtained by phosgenation of aniline / formaldehyde condensates, as well as its liquid reaction products containing NCO groups with deficient amounts (NCO-OH molar ratio 1: 0.005-1: 0.3) of polyvalent ones Alcohols in the molecular weight range 62-3000, in particular in polyols of the molecular weight range 134-3000 which have ether groups, are particularly preferred.

Water glass solutions are understood to mean solutions of sodium and / or potassium silicate in water. Raw technical products, which e.g. B. calcium silicate, magnesium silicate, borates and aluminates can be used. The molar ratio Si0 ₂ : M ₂ 0 (M = metal) can vary within the limits 0.5: 1 to 4: 1. Water glass solutions with a SiO _z : M20 ratio of 1: 1 to 2.5: 1 are preferably used. The concentration of the water glass solution can be selected between 25 to 55% by weight, preferably between 40 to 50% by weight.

The weight ratio between polyisocyanate and water glass in the mixture to be formed can be within wide limits, namely between 75 to 25 to 15:85. A weight ratio of polyisocyanate to water glass of 60 40 to 25:75 is preferably selected.

The preparation of the mixture of polyisocyanates and water glass solutions is easy. It is only necessary to mix the two liquids homogeneously, e.g. B. by stirring by means of stirring bars by hand or by motor-driven agitators that are commercially available. It is also possible to prepare the emulsion on mixing dosing devices. The two liquids are fed to a continuous mixer by means of metering pumps. As a metering pump z. B. gear pumps, piston pumps or diaphragm pumps. As a continuous mixer z. B. Mixing chambers with driven agitator or static mixer suitable, for. B. pipes with differently arranged baffle plates.

The mixture is generally pressed into the formation via lances or pipes or, if necessary, into boreholes made therein. Drill holes must be closed immediately after pressing in, since gelation and subsequent hardening of the mixture only take 30 to 60 seconds to start. Expediently, the mixture is introduced through boreholes via valve closures acting as a valve. B. according to DE-A-2 550 555.

• 1. Beschleuniger, wie sie aus der Polyurethanchemie bekannt sind. Als Beispiele seien metallorganische Verbindungen wie Dibutylzinndilaurat oder tertiäre Amine wie Triäthylamin genannt. Die Zusatzmengen können bis zu ca. 2 Gew.-%, bezogen auf Polyisocyanat/Wasserglaslösunggemisch, betragen.
• 2. Treibmittel wie z. B. Aceton, Methylenchlorid, Monofluortrichlormethan, Dichloridfluormethan, Butan. Die Zusatzmengen können bis zu 30 Gew.-%, bezogen auf PolyisocyanatlWasserglaslösungsgemisch, betragen.
• 3. Verbindungen, die mindestens eine gegenüber Polyisocyanat reaktionsfähige Gruppe besitzen. Diese Verbindungen werden dem Reaktionsgemisch im allgemeinen in Mengen von bis zu 30 Gew.-%, bezogen auf die Wasserglaslösung, zugesetzt. In Frage kommen organische Polyamine wie z. B. Äthylendiamin, Diäthylentriamin, Triäthylentetramin, 4,4'-Diaminodiphenyimethan oder 2,4'-Diaminotoluol, bevorzugt jedoch organische Verbindungen mit alkoholischen Hydroxylgruppen. Hierzu gehörend einfache, ein- oder mehrwertige, vorzugsweise mehrwertige Alkohole des Molekulargewichtsbereiches 32-200, vorzugsweise 62-200 oder die in der Polyurethan-Chemie an sich üblichen höhermolekularen Polyhydroxylverbindungen des Molekulargewichtsbereiches 200-5000, vorzugsweise 200-1000, wie z. B. die an sich bekannten Polyhydroxypolyester oder Polyhydroxypolyäther wie z. B. Polyäther- oder Polyesterpolyole des OH-Zahl-Bereiches von 50-600. Beispiele geeigneter niedermolekularer Alkohole sind Methanol, Äthanol, Propanol, Äthylenglykol, Diäthylenglykol, Triäthylenglykol, Glycerin oder Trimethylolpropan. Beispiele höhermolekularer Alkohole sind Polyester aus Decarbonsäuren, wie z. B. Phthalsäure, Adipinsäure, Hexahydrophthalsäure, Tetrahydrophthalsäure und/oder Maleinsäure und den oben genannten einfachen Alkoholen oder Polyätherpolyole, wie sie durch Alkoxylierung, d. h. insbesondere durch Anlagerung von Propylenoxid und/oder Äthylenoxid an niedermolekulare Startermoleküle erhältlich sind. Geeignete Startermoleküle sind Wasser oder beispielsweise die obengenannten, mindestens zwei aktive Wasserstoffatome aufweisenden niedermolekularen Amine oder Alkohole.

Depending on the type of polyisocyanate used, the selected mixing process, the desired more or less pronounced foaming of the solidifying agent and its consistency, it may be appropriate to add the following additives to the polyisocyanate or the water glass solution or the mixture of polyisocyanate and water glass solution:

• 1. Accelerators as they are known from polyurethane chemistry. Examples include organometallic compounds such as dibutyltin dilaurate or tertiary amines such as triethylamine. The amounts added can be up to about 2% by weight, based on the polyisocyanate / water glass solution mixture.
• 2. blowing agents such. B. acetone, methylene chloride, monofluorotrichloromethane, dichloride fluoromethane, butane. The amounts added can be up to 30% by weight, based on the polyisocyanate / water glass solution mixture.
• 3. Compounds which have at least one group which is reactive toward polyisocyanate. These compounds are generally added to the reaction mixture in amounts of up to 30% by weight, based on the water glass solution. Organic polyamines such as. B. ethylenediamine, diethylenetriamine, triethylenetetramine, 4,4'-diaminodiphenyimethane or 2,4'-diaminotoluene, but preferably organic compounds with alcoholic hydroxyl groups. These include simple, mono- or polyhydric, preferably polyhydric alcohols in the molecular weight range 32-200, preferably 62-200 or the higher molecular weight polyhydroxyl compounds of the molecular weight range 200-5000, preferably 200-1000, preferably 200-1000, such as, for example, which are known per se in polyurethane chemistry. B. the known polyhydroxy polyesters or polyhydroxy polyethers such. B. polyether or polyester polyols of the OH number range of 50-600. Examples of suitable low molecular weight alcohols are methanol, ethanol, propanol, ethylene glycol, diethylene glycol, triethylene glycol, glycerol or trimethylolpropane. Examples of higher molecular alcohols are polyesters from decarboxylic acids, such as. B. phthalic acid, adipic acid, hexahydrophthalic acid, tetrahydrophthalic acid and / or maleic acid and the above-mentioned simple alcohols or polyether polyols, such as are obtainable by alkoxylation, ie in particular by addition of propylene oxide and / or ethylene oxide to low-molecular starter molecules. Suitable starter molecules are water or, for example, the above-mentioned, low molecular weight amines or alcohols having at least two active hydrogen atoms.

Particularly preferred alcohols are the last-mentioned polyether polyols in the OH number range from 50-600. The alcohols can either be added to the water glass solution or the polyisocyanate or as a third component to the polyisocyanate / water glass mixture. Mixtures with additions of the compounds listed above give the best solidification values to date and therefore represent a particularly preferred embodiment of the invention.

4. Emulsifiers such. B. reaction products from stearylamine and ethylene oxide, polyether esters from abietic or oleic acid and ethylene oxide, fatty alcohol polyglycol ether, alkylphenol polyglycol ether, water glass based emulsifiers, e.g. B. Tegosivin from Goldtschmit AG, Amphogenside, z. B. Tego Betaine 27 from Goldtschmit AG, fatty acid amido alkyl dimethyl amine oxide, e.g. B. amine oxide WS 25 from Goldtschmit AG. Such emulsifiers particularly favor the emulsification of the compound according to category 3 in the water glass component and thus also the completeness of the mixing of all components. The emulsifiers are generally added in amounts of up to 15% by weight, based on the polyisocyanate / water gas solution mixture.

5. Thixotropic agents such. B. asbestos flour or other surface-active additives alone or in a mixture with the emulsifiers mentioned under category 4. These thixotropic agents are preferably used if mixtures of water glass solution and the compounds mentioned under category 3 are used. It can also be used to produce stable emulsions over a long period of time, so that two-component systems consisting of water glass solution and additives of categories 1-4 on the one hand and polyisocyanates on the other hand can be handled at the site of solidification. The thixotropic agents are generally added in amounts of up to 5% by weight, based on the polyisocyanate / water glass solution mixture.

6. foam stabilizers such. B. organopolysilioxanes, as are known from polyurethane chemistry.

All of the aforementioned additives can be added either as sole additives or in combination with one another to the mixture or to the component before they are mixed.

Furthermore, it is possible to insert multi-chamber cartridges into the mentioned boreholes, which contain the polyisocyanate, the water glass solution and optionally additives according to category 1-6 in separate containers. After mechanical destruction of the cartridges and mixing of the liquid ingredients z. B through a rotating wooden or metal nail or an anchor rod, the foam-hardening mixture penetrates under the own foam pressure into the formations to be consolidated and sealed and at the same time completely fills the borehole.

The following table and examples provide an overview of the mixtures in question and the practical application of the process.

• MDI ein durch Phosgenierung eines Formaldehyd-Anilin-Kondensates erhaltenes Polyisocyanat, das zu mehr als 50 % aus Diisocyanatodiphenylmethan besteht mit einem Isocyanatgehalt von 31 % und einer Viskosität von 95 mPa-s bei 25 °C.
• Beschleuniger Dibutylzinndilaurat
• Polyol 1 ein Polyätherpolyol, hergestellt aus Trimethylolpropan und Propylenoxid mit einer OH-Zahl von 370 und einer Viskosität von 700 mPa.s bei 25 °C
• Polyol 2 ein Polyätherpolyol, hergestellt aus 1,2-Propylenglykol und Propylenoxid mit einer OH-Zahl von 59 und einer Viskosität von 410 mPa.s bei 25 °C
• Emulgator ein handelsüblicher Alkylphenolpolyglykoläther (Akyporox NP 105, Fa. Chemy, Emmerich) Asbestmehl ein handelsübliches Erzeugnis der Fa. Crace (Silodex 24)
• Stabilisator ein handelsüblicher Polyätherpolysiloxan-Stabilisator (Stabilisator SJ, Bayer AG)

Specifically means:

• MDI is a polyisocyanate obtained by phosgenation of a formaldehyde-aniline condensate, which consists of more than 50% diisocyanatodiphenylmethane with an isocyanate content of 31% and a viscosity of 95 mPa-s at 25 ° C.
• Accelerator dibutyltin dilaurate
• Polyol 1 is a polyether polyol made from trimethylolpropane and propylene oxide with an OH number of 370 and a viscosity of 700 mPa.s at 25 ° C
• Polyol 2 is a polyether polyol made from 1,2-propylene glycol and propylene oxide with an OH number of 59 and a viscosity of 410 mPa.s at 25 ° C
• Emulsifier a commercially available alkylphenol polyglycol ether (Akyporox NP 105, Chemy, Emmerich) asbestos flour a commercially available product from Crace (Silodex 24)
• Stabilizer a commercially available polyether polysiloxane stabilizer (stabilizer SJ, Bayer AG)

In the examples below, a 44% by weight aqueous solution of sodium silicate (SiO ₂ : Na ₂ 0 = 2: 1) was used as the water glass.

example 1

The coal pile in the face went up to 3.50 m into a seam with a 0-10 gon dip and an average thickness of 4 m. This resulted in slope eruptions of up to 7 m in height and 30 m in length. Holes 4.5 m long and 45 mm in diameter were drilled into the coal pile at a distance of 7 m drilled.

The following solidifying agents were used:

Component A: water glass Component B: MDI

Components A and B were pressed in a weight ratio of 1: 1 into the boreholes using a two-component mixing and pressing device via a borehole closure, so that 120 kg of mixture of components A and B came into each borehole.

After 5 hours, the solidified area was broken down using a scraper. It can be seen that the surface of the cracks and cracks in the coal were glued and a good solidification effect had been achieved. The coal pile came off only slightly and normal production continued.

Example 2

In the same mining operation according to Example 1, the consolidation work on the fault zone was continued in the same way as described in Example 1, with the difference that a polyol was additionally added to the consolidation agent. The solidifying agent consisted of the following components:

Component A: mixture of

Component A was obtained from the above. Components prepared immediately before injection by mixing using a mechanical stirrer. The emulsion thus obtained was stable in storage for several hours.

Component B: MDI

The coal pile was solidified according to Example 1; the weight ratio of components A and B was 1.3: 1.

The solidification effect was perfect. There was no turning of the coal pile.

Example 3

When mining a seam with a thickness of 1.3 m and a dip of 0-59 gon, the line seam should be consolidated. The hanging part consisted of solid ribbon slate, the lying part was sandstone. The end of the longwall slope was very loosened in the area of the longwall / line transition when falling in over a length of 1.5-2 m. Gap widths of up to 2 cm were found. Drill holes were made 60 cm above the seam with a length of 2.5 m and 45 mm 0 for consolidation. The distance of the boreholes in the direction of the route was 2.5-3 m. A total of 4 holes were drilled initially.

The following solidified:

Component A: mixture of

Component B: MDI

90 kg of the mixtures A and B (weight ratio 1.5: 1) were introduced into the first borehole by means of a pressing device. 260 kg was pressed into the second borehole, 350 kg into the third borehole and 129 kg into the fourth borehole. The hardening results were so good that there were no outbreaks in the longwall / stretch transition area. Rock samples found in the fracture showed that cracks and crevices in the mountains were completely filled with the hardened foam from components A and B and very well bonded.

Example 4

In a dismantling operation, the transition area longwall / section should be up to 15 m in front of the longwall Polyurethane are solidified. Since the mountains in this area were very wet and the cracks and gaps were filled with water, the known polyurethane system was unable to achieve a sufficient hardening effect. Holes 5 m long and 10 ° rising were then drilled into the slope at a distance of 5 m in front of the longwall face. A total of 1,000 kg of the following mixture has now been introduced through these boreholes:

Component A: mixture of

Component B: MDI

The weight ratio of components A and B was 1: 1.2.

When driving through the solidified fault zone on the route, it became apparent that the slope eruptions that occurred in the non-consolidated area did not occur.

Example 5

On a subway construction site, groundwater and flowing sand were flushed out of a gap (15 m high, 0.7 m wide) into the tunnel space when the soil was excavated. Attempts to solidify the sand by injection into the walls with cement or water glass were unsuccessful. The following water glass-polyisocyanate mixture was introduced with an injection device via injection lances which were introduced into the flowing sand:

Component A: mixture of

Component B: reaction product of 90 parts by weight of MDI with 10 parts by weight of polypropylene glycol having an OH number of 56.

The weight ratio of components A and B was 1: 1. A total of 100 kg of this mixture was injected into the diaphragm wall via the lance. Already after 15 minutes it was shown that the flowing sand was solidified. A further injection lance 1 300 mm deep was introduced into the flowing sand below the first injection point. Via this lance, 70 kg of the mixture of components A and B were pressed at a pressure of 50 bar. With this additional injection it was possible to seal the wall in the area solidified by the injection against water and flowing sand. Test specimens from the consolidated flow sand gave strengths of approx. 12 kg / cm ² (11.8 bar).

Example 6

In a seam with an average thickness of 2.80 m and an incidence of 5 gon, the carbon emptied over a length of 40 m from the head section measured up to 3.50 m. This caused slope outbreaks that severely affected the promotion of the entire strut. The resulting cavities had to be pillared with wood and also had to be pre-charred by hand.

In the critical area, drill holes with a diameter of 50 mm and a slope of approx. 10 gon were made in the coal pile at a distance of 1.5 m and approx. 0.5 m below the hanging. 6 two-chamber cartridges made of polyethylene were inserted into the drill holes. The inner chamber of the cartridge contained the polyisocyanate, the outer chamber contained the following components:

Both components were in a 1: 1 weight ratio in the cartridge. The cartridges were destroyed in the boreholes with the help of rectangular wooden nails with a cat length of 32 mm. The components were mixed well by turning the wooden nails, after which the drill holes were closed with a stopper. When dismantling after 21/2 hours it was shown that through the solidification Effect of preventing the pile of coal from dropping off.

Example 7

A glass tube 60 cm long, an inner diameter of 2.6 cm and a wall thickness of 1 mm serves as the cartridge. This tube is filled with 200 g of the following mixture:

In this tube there is another melted glass tube 59 cm long, 1.6 cm inside diameter and 1 mm wall thickness as an inner cartridge. This inner cartridge is filled with 102 g of a polyisocyanate mixture from the diphenylmethane series with a viscosity of 100 mPa-s / 25 ° C. and an NCO content of 32% by weight.

The cartridge, sealed with a plastic stopper, was inserted into a 30 mm diameter borehole. An anchor rod with a diameter of 24 mm was pushed into the borehole at a speed of 350 rpm. This destroyed the cartridge and mixed the components intimately. The bond length was 110 cm. After 30 minutes the anchor rod was pulled. The anchor rod was only pulled out of the borehole at a tensile load of 24t.

Claims (10)

1. A process for consolidating and rendering impervious geological rock formations and coal deposits, characterized in that intimately mixing water glass solutions with polyisocyanates selected from the group consisting of (i) polyphenyl-polymethylene polyisocyanates which correspond to the phosgenation products of the aniline/formaldehyde condensation reaction and (ii) derivatives of these polyisocyanates which contain carbodiimide groups, biuret groups, urethan groups or allophanate groups and are liquid at room temperature, introducing this emulsion into said formation or said deposit through boreholes or injection lances under pressure and allowing the emulsion to harden in the said formation or said deposit.

2. A process according to claim 1, characterized in that the weight ratio of polyisocyanate to water glass solution is between 75 : 25 and 15 85, preferably from 60 40 to 25 75.

3. A process according to claim 1 to 2, characterized in that up to 2 % by weight of accelerators known from the polyurethane chemistry, preferably metalloorganic compounds or tertiary amines, are added to the emulsion.

4. A process according to claim 1 to 3, characterized in that known propellants in amounts of up to 30 % by weight, relative to the polyisocyanate/water glass mixture are added to the emulsion.

5. A process acccording to claims 1 to 4, characterized in that compounds with at least one group capable of reacting with polyisocyanates and in an amount of up to 30 % by weight, relative to the water glass solution, are added to the emulsion.

6. A process according to claim 5, characterized in that the polyhydroxy compounds known from polyurethane chemistry are used as compounds having at least one group capable of reacting with polyisocyanates.

7. A process according to claim 6, characterized in that polyether polyols with an OH number of from 50 to 600 are used.

8. A process according to claim 1 to 7, characterized in that thixotropizing agents and emulsifiers are added in order to stabilize the emulsions formed from water glass solutions and uni- or multifunctional compounds reacting with polyisocyanates.

9. A process according to claim 1 to 8, characterized in that froth stabilizing agents are incorporated into the emulsion.

10. A process according to claim 1 to 9, characterized in that components of the emulsions to be formed are kept in separate containers in a multichamber cartridge and after being inserted into the formation are mixed together as the cartridges are destroyed.